Functions (mathematics)
In mathematics, a function is a relation between a set of inputs, called the domain, and a set of possible outputs, called the range, where each input is related to exactly one output. Functions can be used to describe a wide range of phenomena, from the Graphite structure of materials to the Neural circuits of the brain. They are a fundamental concept in Mathematics, and are used extensively in fields such as Physics, Engineering, and Computer Science. The concept of a function was first formally defined by David Hilbert, and has since been developed and expanded upon by many other mathematicians. Functions can be classified into different types, such as Linear and Nonlinear functions, and can be used to model a wide range of real-world phenomena, including Tides and Population growth.